My 17 year old brother lives in Missouri with his adopted family. He will be coming to California for my wedding in October. I haven't sent invites yet, however, my mom and sister have told me he has mentioned bringing his 16 year old girlfriend. I hadn't thought about inviting her, but now that they mentioned it I don't know if I should? They are young and they seem to break up and get back together every other weekend (Thanks for the updates Facebook!).
Do I need to follow the usual social unit rule and invite her as well?